1. Field of the Invention
The present invention relates to an ultrasound transducer unit and an ultrasound endoscope equipped with a metal shield member that covers an outer circumference of a substrate that electrically connects an ultrasound element and a signal transmission cable.
2. Description of the Related Art
In an ultrasound endoscope with which it is possible to observe an ultrasound image that is a two-dimensional visible image of a site to be examined, an ultrasound transducer that is provided on a distal end side of an insertion portion normally has a configuration that includes a GND electrode provided on a top face of an ultrasound element such as a single-plate piezoelectric element, and a signal electrode provided on a bottom face of the ultrasound element. The ultrasound transducer has a function that, by application of a voltage from outside to the electrodes on the top and bottom faces of the ultrasound element, radiates ultrasound that accompanies vibration of the ultrasound element towards a site to be examined, and receives a reflected acoustic wave from the site to be examined and converts the reflected acoustic wave into an electrical signal.
Further, a configuration is known in which transferring of at least electric power and electrical signals between the ultrasound transducer and an external device is performed through a signal transmission cable that is inserted through the inside of an insertion portion of the ultrasound endoscope and is electrically connected to the signal electrode of the ultrasound element, within a transducer case that holds the ultrasound transducer.
Note that the signal transmission cable includes a plurality of cables in which the electrical safety is ensured by providing a signal wire and a GND wire that is positioned on an outer layer of the signal wire on the same axis.
In this case, a configuration is also known in which electrical connection of a signal transmission cable to an ultrasound element is performed through a substrate, as disclosed, for example, in Japanese Patent Application Laid-Open Publication No. 2006-25892.
Further, since it is necessary from the viewpoint of electrical safety to also securely cover an exposed area of an electrode in the substrate or the ultrasound element, such as an electrode to which the signal transmission cable is connected in the substrate and an electrode to which the substrate is connected in the ultrasound element, in Japanese Patent Application Laid-Open Publication No. 2006-25892 a configuration is disclosed in which, inside a transducer case that holds an ultrasound transducer, the substrate is hermetically sealed and covered from outside using a metal shield member that is grounded.
Note that, hereunder, a structure in which a metal shield member is covered over the outside of a substrate in a state in which a signal transmission cable is electrically connected to the substrate inside a transducer case is referred to as an “ultrasound transducer unit.”
As a configuration for grounding a metal shield member, a configuration is known in which the other end of ground wiring having one end electrically connected to a GND pattern provided on a substrate inside the metal shield member is led out to outside of the metal shield member from inside the metal shield member through an opening in a rear end of the metal shield member before hermetic sealing is performed, and the aforementioned other end is connected by a solder or the like to an outer circumferential face of the metal shield to thereby perform grounding.